As an electroacoustic transducer of a mobile device or the like, there is an electro-dynamic electroacoustic transducer. The electro-dynamic electroacoustic transducer generates oscillation amplitude by using the action of a magnetic circuit. However, since the magnetic circuit is constituted by a large number of members such as permanent magnets or voice coils, in the electro-dynamic electroacoustic transducer, there is a limit to reduction of thickness.
As an electroacoustic transducer to replace the electro-dynamic electroacoustic transducer, there is a piezoelectric-type electroacoustic transducer. The piezoelectric-type electroacoustic transducer generates oscillation amplitude by using expansion and contraction motion which is generated by applying an electric field to a piezoelectric vibrator. Since the piezoelectric-type electroacoustic transducer does not need a large number of members in order to generate the oscillation amplitude, the piezoelectric-type electroacoustic transducer has an advantage in reduction of thickness.
As techniques relating to the piezoelectric vibrator, there are techniques described in Patent Documents 1 to 5. The techniques described in Patent Documents 1 and 2 are techniques in which a vibrating member with a piezoelectric vibrator attached thereto is supported by a supporting member through an elastic member. In Patent Document 3, there is disclosed a piezoelectric acoustic device in which the density of members which are connected in sequence from a piezoelectric element in the peripheral direction thereof is gradually decreased. In Patent Document 4, there is disclosed a wave-receiving type piezoelectric element in which a piezoelectric vibrator is sandwiched between a pair of rigid members. The technique described in Patent Document 5 is a technique in which a cut groove is provided in a piezoelectric vibrator which is constituted by fixing a piezoelectric element between two vibrating plates through solder.